An aggregation method of wind farms model for studying power system low frequency power oscillation

An aggregation method to build the model of grid-connected wind farms consisting of double-fed induction generators (DFIGs) for studying power system low frequency power oscillation is presented. Firstly in this paper, the accurate dynamic model of a wind farm expressed in the form of transfer functions is derived based on the dynamic model of single DFIGURE Secondly, an estimation of impact of grid-connected wind farm on power system small-signal angular stability is established. The established estimation indicates the aggregation principle of dynamic model of wind farm for studying of power system low frequency power oscillations. The aggregation should ensure that the frequency response of aggregated model ought to be approximately equal to that of accurate dynamic model at the electromechanical oscillation frequencies of concerns. The dynamic model of a DFIG can be used as the aggregated dynamic model of wind farm by use of numerical fitting method based on the aggregation principle, which can reduce the calculation complexity in the power system small signal stability analysis. In the paper, an example 16-machine 68-bus power system with a grid-connected wind farm is presented.